The statements made in this section merely provide information related to the present disclosure and may not constitute prior art, and may describe some embodiments illustrating the invention.
High temperature polymer gels are needed for shutting off unwanted water in oil and gas reservoirs and/or shutting off gas in oil reservoirs. Water-soluble polymers are typically employed that are introduced into a formation and are subsequently crosslinked so that the polymers gel to facilitate shutting off the desired zone(s) of the formation. Metal crosslinking agents have been used in certain situations to crosslink polymers to form polymer gels. Metal crosslinking agents require complexing agents to delay crosslinking and many of those metal crosslinking systems gel within minutes at elevated temperatures.
Organic crosslinking agents may be preferred over metal crosslinking agents in certain instances due to environmental and other factors. One of the shortcomings of many organic crosslinking agents, however, is that they may also gel too rapidly in high temperature environments, which may be too short to facilitate injection and proper placement of the polymer fluid. Other organic crosslinking agents may be used in high temperature environments that facilitate delayed gelling of the polymer fluids. The gel times provided by such high temperature organic crosslinking agents, however, may be measured in days rather than hours, and therefore may be too slow to provide an effective treatment.
Accordingly, there is a need to provide a polymer fluid that provides a suitable gel time in high temperature environments that is neither too short nor too long.